Drawing sheet glass



' Asheet glass can vbe obtain from a furnace f Patented 15, 1927.

UNITED As'rnfras 1,618,107 AP A'1l3N'r- Aorifice.

JosEPH A. or T oLEDmoHIo, AssIGNoB 'ro THE :ABBEY-OWENS sHEE'r GLASS comm, or TOLEDO, oHIo, A conPonATIoN 'or QHIo.

muwme SHEET Grass.

Appncatipn mea ne'cemiar 31,1923.' serial No. 683,596.

This invention relates to improvements linthe art of drawing sheet glass, and more par-Y ticularly tol the art Tof drawing the sheet, in cont.nuo'us form,'downwardly 'from the'Y molten source. i

The principal object'of the invention 1sv to increase the productive capac1ty of the continuous tank furnace which furnishes the molten glass from which the-sheet is drawn. p

Bv em lo ine` the principles u p y b production of tion a much greater -dail of givensize. In the mostsucc forms of sheet glass drawing apparatus heretofore used, :the glass-producing materials are melted 1n one end of a rather long tank furnace, the

molten' glass flowing through the settling and` refining portions of the tank to thefopposite end where the surface lass' flows into a shallow receptacle from w ich the sheet is drawn. Experience has shown that installations of this type, although the mam tank portions may hold a body of glass having adepthof several feet, only the upper stratumf to thedepth olf avery few inches flows freely through the tank, andthe lower strata of themolten glass Vare practically stagnant. Now itis essential that the molten :ofglass -remaina certain length of time in the tank te reach the proper stage of refinement beforev it may be successfully drawn Vinto sheet form, an'd the surface area. of this type of tank must bear \snch a relatlon to the amount of glass drawn from the tank that the surface glass will remainv in thetank for the proper refining period. For ex. ample, if oneattempted to draw. two sheets v from'a furnacel designed to Vfeed a single not have time to reach-the properly refinecylyl/ sheet, the drain on the tank would be such that the surface stratum of glass would flow toon rapidly through the furnace and would cond'tion. It has been considered necessar in such cases to greatly mcrease the surfac sheet could bes'ubstantia-ll'y doubled without i' increasing-the rate ofjowth'rough the urn ace over that in present installations. This end is reached by withdrawing the molten and now. inactive portions of the molten i ool. A pot or receptacle adapted to hold a relatively small and substantially constant onantityofmolten glass is positioned beneath thev end of the mam retinlng tank, end a'regulatedlstream of molten lass is allowed to iiow 'from the bottom o the -refining'tank into ithis pot. The pot .is provided with a" `.narrow elongated slot in its lower portion throughwhich the molten. glass Hows onto and down theopposite sides ofa wedge# shaped slab or directfng member supported -beneath'the pot. The thin streams of glass flowing. down the opposite faces of the slab -unitefat the lower edge of the slaband are drawn downwardly therefrom in the form of a single sheet. Thisv pot which holds lthe working supply of molten glass, is substantially enclosed except for'tlre opening in its tjop for the incoming stream of glass from the reiinin tank, ,and the slot in its bottom` throughw ich .theglass flows on to the sheet-'forming slab.- .In this manner the working supply of moltenglass is protected against dirt or solid products of combustion. VThe pot is supported within a furnace or heating chamber which practically sur-v rounds the 'pot on all 'sdesij By regulating the heat in this chamber the Vmolten glass, may be constantly maintained-at the proper 'working temperature. This heating chamber, which is directly beneath that portion of the retining'tankfrom. which4 the molten l,glass flows into the pot, also serves to heat the molten glass within the refining tank adjacent the exit'orlvice, to facilitate the free low of molten glass from the lowerd area of the tank so that the rate of iowv for ,strata within the refining tank.

the increased outpnt would still the mobile surface glass to remain 1n thetank the necessarylength-of time'.

According to this invention, the increased production is accomplished by increasing the depth of 4flow of the molten glass through the. tank.A For example, if the lowing stream of glass Weremade twice as, deep 'as before, the size, 'or the .drawing rate of the allowJ all of `\l` Asheet flowed or 'drawn downwardly may be formed 'much more rapidly than one drawn'upwardly, since in the first case the force ofgravity assists, rather than retards thefoperation.` By withdrawing .the molten leo los

vglass from the bottom of the tank, the formerly stagnant lower strataare kept in mo- :tion and a greatly increased depth ff stream flow through the tankis provided, whereby the glass may be flowed from the tank rapidly and inincreased quantity, without putting too great a drain on the tank. By first flowing this molten glass into an enclosed pot of substantially constant capacity, which pot is enclosed in a heated chamber, the tem-V perature and head of the molten glass which flows downwardly onto the lforming slab may be accurately and constantly controlled. 1D The finalv result is to rapidly produce an increased quantit of sheet glass from' a tank of relatively smal capacity.

The above, and other objects and advantages of this invention will be better underl stood from the following detailed description of certain forms of apparatus embodying the principles of this invention.

In the accompanying drawings:

Fig. 1 is a longitudinal section through the 20 refining end of the tank furnace, and a transverse vertical section through the pot and sheet-'forming mechanism. This view is taken substantially on the line 1-1 of Fig. 2.` Fig. 2 is a. Vertical section taken at right Y angles to Fig. 1 and substantially on the line 2-24ofFig. 1.

Fig. 3 is a view similar to Fig. 1, showiigb a modified form ofthe sheet-forming s a Fig. 4 is a transverse vertical section through still another form of slab.

Referring first to Figs. 1 and 2 of the drawings, lindicates the continuous tank furnace, the'lmolten glass 2 being first produced in the melting end of the furnace, not

here shownl but being at the right of Fig. 1, Y

- thisglass flowing slowly through the furnace to the refining en d 3. Adjacent the end of the refining portion of the tank, an exit orifice 4 is provided in the bottom. wall of the tank. Thislorifice may be of" any ldesired contour, but may be conventionally in the form of a round drain hole, as here shown,

. with the side walls 5 projecting upwardly somewhat into the tank, whereby the eX- treme lower stratum of glass in the refining tank will be held back' from the exit orifice. A plugl or other closure member 6 is suspended within the molten glass above the `opening 4, and this plug may be lowered or raised to entirely cut off or partially impede the flow of glass through the opening. -In this way the-size of the stream of molten glass?,

.which flows downwardly from the refining tank, may be regulated as desired. suitably supported beneath the'o-pening 4 is a comparatively shallow refractory pot 8, the bottom walls 9 of which preferably slope downwardly toward a centrallypositioned elongated slot 10' extending transversely of -the bottom of the pot. .The total 'area of this slot 10 will besubstantially the same, or.

' 'slightly less'than, the area of orifice 4 in the refining tank, so that the amount. of molten glass which normally flows downwardly from potv 8 through slot 10 will substantially equal the amount flowing downwardly into the pot from the refining tank thereabove. Pot 8 is preferably substantially enclosed by a c-over-plate 11 provided with a central vertical passage surrounded by the cylindrical collar or ring 12, which extends up to and fits against the bottom of the refining tank at the flared lower end of orifice 4.

Directly beneath the slot 10 is positioned a refractory slab or forming member 13, preferably formed with a glass-receiving recess 14 in its upper end, and havin downwardly converging side walls. 15 wh1ch meet at the lower edge 16 of the slab. The stream of molten glassv 50 which flows down through slot 10 from the pot 8 is received in recessv l 14 at the upperend of the slab, and this glass spills or overflows'over the upper edges of the slab and flows in thin equal streams down the converging sides of the slab. The sheet of glass 17 is drawndownwardly from these streams; of glass which meet and combine at the lower edge 16 of the wedgeshaped slab. v

As Shown in Fig. 2, the lower edge 16 of slab 13 may be made curved or arcuate, so that the lmolten glass flowing into the central portion of the sheet remains on the slab longer than the molten glass lforming the sheet edges. This added retarding leEect at the center, caused by the adhesion of the glass to the slab, will offset the more sluggish flowing action o f the glass at the edges vof the stream flow.

Any suitable means,` such as indicated conventionally by rollers 60, for drawing and guiding the `glass sheet 17 downwardly, and for supporting and carrying away the Vformed sheet may be used'. Many forms of apparatus for this purpose have already been disclosed in the prior art.

The forming slab 13`is substantially en. I

closed by the protecting chamber 18, and the interior of this chamber will be heated in any suitable manner, for example by burners such as those shown at 19, to keep the slab and the streams of molten glass which flow 'down the sides of the slab at thel proper temperature for the sheet-forming operation. Preferably, the upper portions 20 of the side wallsof chamber 18 will be sloped inwardly and join with the bottom walls 9 of pot 8 adjacent the sides of slot 10. This is to allow a second furnace chamber 21,

which substantially surrounds the entire pot 8, to 'direct its heat'againstas large a-.portion as possible of the loi'v'er surface of the pot. This furnace or llc-ating chamber 21 may be heated by a plurality of burners such as indicated at 22, and serves not only to-keep the pot 8 and the working supply of glass theremat the proper temperature, but also directs its heat'against the bottom 23 of the refining tank adjacent thelorifice 4 to -keep'the glass i t v l' ten 'glass flow down the sides of theslab as 'in' the form previouslyl described, and are..

' ply of molten glass-contained inthis pot.'

. prevailing in the glass supply is als i within the refining tank adjacent this-orifice at a suincientlyhighy temperature to flow freelyintothe t8.

Pot 8 w1ll beV provided with; a 'suitable overflow spout 24 at one side adjacentits upper edge to limit the 'maximum working sup- Any excess of molten glass, which may flow through orifice 4 over that issuing from the pot through slot 10, will overflow through spout 24 and may beconv'eyed out of the furnace chamber 21`through any suitable drain 2 5'. By suitably regulating the position of the plug or closure 6 with relationto orifice 4, the volume of the stream 7 flowing downwardly into fthe pot is so regulated that little or no overiow need take -`Aplace through spout24.J

It will be noted that a substantiall con? stant head of glass is maintained in t e potabove the orifice regardless of any liuctuations in depth lof the main body of glass in the tank furnaoe.` Also, it will be noted that this working supply of glass .in the pot 8 is entirely enc osed and `protected against dirt or the 'directfcont'act ofthe heating gases within the chamber 21. By properly regulating the burners 22, the temperature of this working supply'of glass lin pot 8 may be maintained fpractically. constant,l entirely,"

independent o the temperature conditions s furnace from'which the In Fig. 3 a somewhat modified form of pot. and sheet-forming slab is disclosed. .In this construction, theslot 26 inthe bottom of the pot 27 is4 made considerably wider than the slot 10 in' the construction previously A'described, and the upper end of the wedgeshaped slab 28 is positioned within the working supply ofmolten glass 29 in--'the'pot. Slab28 projects ldownwardlylthrough stot 26 so as to divide this slot intoa pair of narrow elongated assages at ,either side of the slab through w ich thin' streams of moly drawn away fromthe lower edge of the slab inthe form-of glass sheet 30.v Refractory or metallic lining members 31 having outwardly flared lower ends as at 32, are preferably Aclzaure'd to the bottom walls of pot 27 along line-forming'deposits along the side walls of` the slot 26.

slab connects with a passage or hollowp ,In the formz of slab sadisclosea in Fig. 4, the glass-receiving recessj34 at the top of e rtion 35 extending downwardly throughpthe l slab to the lower edge 36..- Aportion of the 4molten glass flowing down 'from 'the supply. 'pot into the recess 34 will overflow as before prisin in thegb sides of slot' I26. These flared lower ends 32 will tend to permit amore free and evenA flow@l of glass down the side walls of the slab without the. formation of dog-metall or other down the outer' side walls of theslab, andV another portion will ilow down from recess V34 through the interior ofthe slab and join with the side streams 27 to form the sheet 38 fro 1. The method-ofxrna-king sheet glass, con# sisting in producing molten glass in a con-- tinuous-tanklfuinace, flowing molten glass from,.the lowerfstrataof glass inthe tank '1n a regulatedistream into a.l se arately enclosed pool, and drawing glass sd nwardly from the pool in sheet form.

2. The method of, making sheet glass,con`.

sisting in producing molten glass in a. continuous tank furnace, flowing molten'y glass from the IOWer'istrata of glass in thetank into: agseparatel j enclosed pool 'and flowing glass downwardly from the podl onto a'slab lfrom which it is drawn in sheet form. f

3. The method of making sheet glass, con sisting in producingmolten-glass injacontinuous tank furnace, iiowing.- molten glass from the' lower strata 'of glass in the tank in to a separatelyI enclosed vool,.and flowing glass downwardly from t e .pool onto'thel top of a downwardly tapered slab, and ther.

drawing awa in sheet form the glass which Hows downt 'e convergin sides of the slab;

4. The .method of maing sheet glass, l-whichconsists in flowing molten glass onto' and down the sides of a directin member,

impeding the' central portion of t e flowing vstreams more than the'edge portions, and

drawing away the 'uniting "streams in sheet form.

5. Apparatusfor making-'sheet glass,.com a tank furnace having an aperture ottom of its refining end, a pot posi# tionedbelow the `aperture and having a slotted bottom, and means :for 'drawing away in sheet form'the glass which passes down-- wardly through the-slot'.` 1

' 6. Apparatus for making sheet glass, comins prising a/ tank furnace having an aperture in the bottom o f'its'refining-end, means for ture and having a slotted bottom, and means 'for drawing vaway in sheetform the glass which passes downwardly through the slot."

7. Apparatus for-makil'ig-sheet glass, comrisinga tank furnace'having an aperture l1n the bottom of refiningv end, a pot` posiregulating-mellow of l'molten glass throughv l the aperture, a pot positioned below the aper- 125 tioned. below the aperture and having a slotted bottom, a heating chamber within which the pot is enclosed, and means for drawing-away in sheet form the glass which passes downwardly through the slot.

8. Apparatus for making sheet glass, comprising a tank furnace having an aperture in the bottom of its relining end, means for regulating the How of molten glass throughl Y cover-plate.

the aperture, a pot positioned below the aperture -and having a slotted bottom, a heating chamber within which the pot is enclosed, and means for drawing away in sheet 10. Apparatus for making sheet glass,

comprising a tank furnace having an aperture in the bottom of its refining end, a pot positioned below the aperture and having a slotted bottom, a slab positioned below the slot, and means for drawing away in sheet form` the glass which flows from theI slot upon and around the slab'.`

11. In anapparatus for making sheet glass,'an enclosed pot for supporting a pool of molten glass, the pot having an elongated slot in its bottom through which` the glass flows to form the'sheet, and a top having an- `aperture therein through which the supply ofmolten glass is replenished. 12. In an ap aratus for making sheet glass, an enclose i potfor supporting a pool of molten glass, the pot having an elongated--slot in its bottom through which the glass flows to form the sheet, and a coverplate forthe pot having an aperture through which the supply of molten glass is replenished. 'l

l 13. In an apparatus for making sheet glass, an enclosed pot for supporting a pool of molten glass, the pot having an elongate slot in'its bottom through which the glass flows to form the sheet, and having an overflow opening at one side for maintaining a constant head of glass in the pot,and atop for the pot having an aperture therein replenished.

14. In an apparatus for making sheet glass, an enclosed pot forsupportinga pool.

of molten glass, the ot having an elongated slot in its bottom through which the glass iows to form thesheet, and a top for the `pot having an aperture therein through which the supply o molten glass is replenished, in combination with a heating chamber substantially surrounding the pot.

' meet, in combination with 15.- In an apparatus for making sheet glass, an enclosed pot for supporting a pool of molten glass, the pot having an elongated slot in its bottom through which the glass flows to form the sheet, and a cover-plate for the pot y having an aperture through which the supply of molten glass is replenished, in combination with a heating chamber substantially surrounding the pot and 16. In an apparatus for making sheet glass, a vertically positionedslab,/ having downwardly converging sides, a recessed top, and a central slot extending from the top recess through the lower edge of the slab. S0

17. In an apparatus for making sheet glass, a vertically positioned slab, having downwardly converging sides, a recessed top, a central slot extending from thev top recess through the lower edge of the slab, '85

and heating means within the slab at either side of the slot. y

18. In an apparatus for making sheet glass, a vertically positioned slab,v having downwardly converglng sides, and a curved lower edge at which the converging sides meet.

19. -In an apparatus for making sheet glass, a vertically positioned slab, having downwardly converging sides, and a curved lower edge which is lower atl the center than adjacent the sides of the slab, .the converging sides meeting at the curved edge.

20. In an lapparatus for making sheet glass, a .vertically positioned slab, having downwardly convergingv sides, and-a curved lower edge at which the converging sides Veans for flowing molten glass onto and dow the sides of the slab, and means for drawing this glass downwardly from the curved lower edge in sheet form.

21. In an .apparatus for 'making sheet glass, a vertically positioned slab, having downwardly converging sides, and a curved lower edge which is lower at the center than.

.adjacent the sides ofthe slab, the converging' sides meeting at the curved' edge,in combid nation with means for iowing molten glass onto and down the sides of the slab, and

means for drawing this glass downwardly from the curved lower edge in sheet form.

,22. `In apparatus for making sheet glass, a

vertically positioned slab, having a recessed curved lower edge at which the converging sidesmeet, m combination withI means for flowing vmolten glass into thev recess and thence down thesides of the slab, and means 4for drawing thls glass downwardly from 1,25

ber,w 1923. y

. v .JOSEPH mREECE.

througlr which the supply of molten glass .is (,t'Op, downwardly converging sides, and a 120 

